1. Preheat the oven to 220° C / 425° F. Lightly flour a baking tray. Sift the flours, cream of tartar, bicarbonate of soda and sea salt into a large bowl. Make a well in the centre of the mixture.

2. Pour in almost all the buttermilk, then stir with a wooden spoon until thoroughly combined. Feel the dough. It should be slightly sticky. If too dry, add the remaining buttermilk. Transfer the dough to a lightly floured work surface.

3. Gently knead the dough for 1 minute (do not over knead).

4. Shape the dough into a round and place on the prepared baking tray. Cut a 1.5cm (½-inch) deep cross into the dough and sprinkle with the sea salt flakes.

5. Bake in the preheated oven for 30 minutes, or until golden and cooked through (test with a wooden skewer – if it comes out clean, it’s done).

6. Remove from the oven and transfer to a wire rack. Allow to cool then cover with a dampened towel until required.